The present invention generally relates to pollutant detection, and more particularly to the analysis of water supplies for the measurement and characterization of organic contaminants therein.
The presence of organic contaminants in underground water supplies and other water sources can present significant pollution problems. A wide variety of organic materials may be present in subterranean water-containing regions, depending on how the overlying land under consideration has been used. For example, many different organic solvents and related compositions (e.g. both unhalogenated and halogenated compounds) may exist in groundwater supplies at factory sites and other locations where extensive use of these chemicals has occurred over long time periods. Such materials are typically characterized as "volatile organic contaminants (compounds)" or "VOCs". Of particular concern are halogenated (e.g. chlorinated) solvents including trichloroethane, dichloroethane, and others. However, in addition to halogenated solvents, a wide variety of other organic compositions shall be encompassed within the term "organic contaminants" as discussed below including but not limited to methane, vinyl chloride, ethane, ethene, benzene, toluene, xylene, and others. Of equal concern is the presence of petroleum-based fuels (e.g. jet fuel, gasoline, diesel fuel, and the like) in underground water-containing regions at various transportation-related facilities including but not limited to gasoline stations, airports, military bases, and the like. Regardless of the particular organic contaminants under consideration, the presence of these materials at or near underground or above-ground water supplies is a substantial problem of considerable importance. Accordingly, the present invention shall not be restricted to the analysis of any given organic compounds.
Many different methods have been used to analyze water supplies at various test sites. Of particular importance is the analysis of aquifers for high concentrations of organic waste products. The term "aquifer" as used herein basically involves a large underground water source located within vast regions of rock or soil. Prior testing methods have involved the drilling of deep wells directly into an underground water-containing site (e.g. an aquifer), followed by the placement of screening materials within the wells. Dedicated submersible pumps were then positioned in each well to withdraw numerous water samples for delivery to the well head. Thereafter, the samples were analyzed to determine the type and amount of organic contaminants in the samples.
While this method provided important information regarding the levels of organic contamination in the water supplies of concern, it did not supply any data involving the vertical distribution and "stratification" (e.g. three-dimensional location) of organic contamination in the water supplies. This type of data is important in determining the spatial distribution of organic contamination including how far (both vertically and horizontally) the contaminants have dispersed in the water source of concern. The testing methods described above are not "location sensitive" and provide little information concerning the specific three-dimensional distribution of organic contamination. Traditional testing methods also require a large amount of expensive equipment, are labor intensive, and involve complex operating procedures. Finally, conventional processes which require the removal of numerous liquid samples for individual testing typically generate large quantities of waste products (e.g. residual sample materials) which, if sufficiently contaminated, can present significant disposal problems. Prior to development of the present invention, a need therefore remained for an efficient testing system which avoids these disadvantages and enables underground water supplies (as well as above-ground water sources) to be tested in an accurate, rapid, and effective manner.
The claimed invention represents a unique and highly-efficient alternative to the methods listed above. It does not require extensive equipment (e.g. submersible pumps) and complex operating procedures. It can also analyze large water supplies without extracting any sample materials so that waste problems are avoided. Finally, the method and apparatus described below enable the water supply of interest to be simultaneously analyzed at multiple locations so that the contamination may be "mapped". Decontamination of the water source can then occur in a more site-specific and accurate manner. The present invention therefore involves a highly effective testing system which represents a substantial advance in the art of pollution detection and remediation as discussed further below.